The testing of reusable bottles and reusable containers for liquid, solid, and gaseous contaminants is an important technical problem, especially since the introduction of plastic bottles and plastic containers, since the harmful substances such as poisons diffuse into the wall material and, upon refilling with the product in question, for example lemonade, cola, fruit juice, etc., have an adverse affect on the taste.
In German P 41 21 429.3, an efficient method and devices are proposed for solving the problem of harmful substances by using gas samples drawn from the bottle or the container above the level of the liquid. One disadvantage of this approach resides in the fact that materials with extremely low partial pressures, such as, for example, high-boiling vegetable oils, hydraulic oils, inks, water-soluble dyes, naphthalene, etc. cannot be detected reliably if at all.
In U.S. Pat. No. 4,858,768, a method is proposed for investigating, in detail, a liquid drawn from the bottle or container to determine whether the liquid corresponds to the original product in the bottle or container and, if not, rejecting the bottle or container from the refilling process. This is uneconomical since re-usable bottles and containers very rarely return with original product to the filling plant. Consequently, a number of bottles are unjustifiably rejected because many fermentation products, rinsing with water by the consumer, drying out, etc alter the composition of the original product but would not cause the bottle or container to be termed contaminated. In addition, the sole examination of the residual fluid or residue contained in the bottle or container as intended in U.S. Pat. No. 4,858,768 does not solve the problem since harmful substances adsorbed in the walls of the bottle or container would not be detected.